1. Field of the Invention
The present invention relates to an eversion nozzle, a method for everting a tubular liner bag by means of the nozzle, and a process for repairing an underground tubular conduit by lining the inner wall of the tubular conduit with the tubular liner bag.
2. Description of the Prior Art
When an underground tubular conduit, such as pipelines and passageways, becomes defective or too old to perform reliably, the tubular conduit is repaired and rehabilitated without digging the earth to expose the tubular conduit and disassembling the sections of the tubular conduit. This non-digging method of repairing an underground conduit has been known and practiced commonly in the field of civil engineering. Typically, the method is disclosed by Japanese Provisional Patent Publication (Kokai) Sho 60-242038.
According to this publication, this method of conduit repair comprises inserting a sufficiently long tubular flexible liner bag into the tubular conduit to be repaired by means of a pressurized fluid, like air and water. The tubular liner bag is made of a flexible resin-absorbent material impregnated with a thermosetting liquid resin, and has the outer surface covered with an impermeable plastic film.
More particularly, according to the publication, the tubular flexible liner bag is closed at one end and open at the other; the tubular flexible liner bag is first flattened, then, the closed end of the tubular liner bag is tied to a control rope; the open end of the tubular liner bag is made to gape wide and hooked (anchored) at the end of the defective or old tubular conduit in a manner such that the wide-opened end of the liner completely and fixedly covers and closes the conduit end; a portion of the liner is pushed into the conduit; then, the pressurized fluid is applied to the said portion of the tubular liner such that the fluid urges the tubular liner to enter the conduit. Since one end of the tubular liner is hooked at the end of the conduit, it remains there while the rest of the flexible liner bag is turned inside out as it proceeds deeper in the conduit, and this manner of insertion is exactly what is meant by the term "everting" as used above and it shall mean so throughout this application document. When the entire length of the tubular liner bag is everted (i.e., turned inside out) into the conduit, the control rope holds the closed end of the tubular liner bag to thereby control the length of the tubular liner in the conduit. Then, the everted tubular liner is pressed against the inner wall of the conduit by the said pressurized fluid, and the tubular flexible liner is hardened as the thermosetting liquid resin impregnated in the liner is heated, which is effected by heating the fluid filling the tubular liner bag by means of a hot steam, etc. It is thus possible to line the inside wall of the defective or old conduit with a rigid liner without digging the ground and disassembling the conduit sections.
Now, in a more modern method, an eversion nozzle such as the one (101) shown in FIG. 14 has been employed for the purpose of causing the tubular liner bag to evert more effectively.
In the case of FIG. 14, the eversion nozzle 101, which is an elbow pipe having a right-angled bend, is installed in the bottom of a manhole 108, and the open end of the liner bag 106 is passed through the nozzle 101 from the inlet port and turned inside out at the outlet port thereof to wrap over the brim of the outlet port and fixed thereat. At the inlet port of the eversion nozzle 101 is fixed the lower end of a guide tube 107.
That portion of the tubular liner bag 106 yet to be turned inside out (everted) is suspended inside the eversion nozzle 101 and the guide tube 107 and its closed end portion is coiled on the ground ready to real off. The upper end of the guide tube 107 is fixed at a support frame 111 installed on the ground. Furthermore, one end of a draining hose 110 is connected to the eversion nozzle 101, and the other end of the draining hose 110 is held over a water tank 137 to pour water therein.
Thus, when water is charged into the guide tube 107 from the charge hose 112, the tubular liner bag 106 is caused by the water head to evert into the tubular conduit 113, as indicated by the arrows in the conduit 113.
Problems the Invention Seeks to Solve
As is the case with the manhole 108 of FIG. 14, generally a manhole to a sewer pipe is designed to have a smaller diameter at the entrance than inside. Commonly, the interior diameter d.sub.1 is 900 mm and the entrance diameter d.sub.2 is only 600 mm.
Therefore, in order to introduce an eversion nozzle such as the one 101 into a manhole 108, the length L of the nozzle ought to be substantially smaller than the entrance diameter d.sub.2 of the manhole 108. However, usually the length L of a nozzle is designed to be at least twice as great as the inner diameter D thereof, so that when the entrance diameter of the manhole is 600 mm, the length L must be less than 600 mm and hence the inner diameter D of the nozzle must be substantially smaller than 300 mm. Consequently, the tubular liner bag that can pass the nozzle must have outer diameter less than 30 mm. For this reason, the conventional eversion nozzle 101 could not be used in the cases where the inner diameter of the tubular conduit to be repaired is 300 mm or greater.
Thus, when a tubular conduit having an inner diameter of 300 mm or greater was repaired, it was necessary to install an eversion nozzle outside the manhole, that is, on the ground, attach the tubular liner bag to the nozzle, and evert the liner bag from outside the manhole. This resulted in a situation wherein the length of that part of the everted liner bag which is suspended in the manhole and not used to line the tubular conduit is substantially large, and this was very uneconomical. Especially when the depth of the manhole was great, not only the wasted amount of the tubular liner bag was large, the labor of removing that wasted part from the manhole was time-consuming.
The present invention was contrived in view of the above problems, and it is, therefore, an object of the invention to provide a new eversion nozzle and a new method for everting the tubular liner bag with which it becomes possible to line a tubular conduit having a relatively large diameter without wasting much length of the tubular liner bag. Thus, a new process of repairing a tubular liner conduit is also proposed in this invention.